INTRODUCTION / PURPOSE Desenvolvimento Rodoviário S.A (DERSA) operates a large ferry fleet in the Sao Paulo, Brazil region. The fleet has experienced severe problems arising from "sludge formation" in the diesel fuel delivery system, including tanks. The consequences of this sludge formation include clogging of fuel supply lines, an unacceptably high frequency of filter replacement as well as significant, undesireable exhaust emissions.

The purpose of this report is to document the solution to this sludge problem through use of an innovative additive; Fuel Right 15K.

Historical data provided by DERSA identified the ferry
with the highest incidence of problems as ferry boat
number #17; this ferry was therefore chosen by the
DERSA Operations management as the appropriate vessel for evaluating Fuel Right 15K. Ferry #17 experienced continual filter clogging problems, often requiring stops to change the filter elements and, as an old vessel, likely to have high sludge formation potential in reservoirs. This ferry is powered by four (4) Scania engines and equipped with two fuel tanks, each with a capacity of 7500 liters.

The objectives for this trial were:

  1. Eliminate formation of "sludge" in fuel tanks and fuel supply lines

  2. Protect the environment by reducing or elimination particulate emissions

  3. Reduce the number of forced stoppages to change clogged filter elements (Racor filters)

It is important to point out that, in addition to the above objectives, the following were also achieved:

  • Reduction in diesel fuel consumption

  • Elimination of internal corrosion in the tanks and supply lines. This parameter, despite having been verified in other cases with Fuel Right 15KR will only be able to be verified after a long interval of time, since the corrosion process is quite slow.

BACKGROUND INFORMATION As diesel is a hygroscopic product, its affinity for water enables growth of microorganisms wherever the fuel is stored. The ferry diesel tanks are large and the fuel consumption is also quite high considering that these ferries operate in duty cycles of up to 14 hours. The ferrys therefore usually operate with tanks that have empty space and at high levels of moisture and elevated temperatures. Since the cooling of injector nozzles is made by diesel fuel itself and the fuel consumption is independent of amount remaining in the tank, the lower the volume of stored diesel the higher will be the temperature inside the tank due to the low thermal dissipation rate of the system. As a consequence of moisture there is condensation that accumulates at the bottom of the tank, creating an extremely favorable environment for the growth of bacteria colonies that then form the biofilm (sludge layer); moreover, this biofilm will create conditions that lead to microbially induced corrosion (MIC).

These microorganisms (bacteria and fungi) are present throughout the fuel chain, from its extraction platforms to the tanks of vehicles, vessels or other equipment. Bacteria are the microorganisms that form sludge and cause microbial corrosion in fuel tanks, supply lines and fuel pumps. Free-floating (planktonic) bacteria in fuel do not create problems; sludge is formed when these bacetria attach to fuel tanks as “sessile” bacteria and form the BIOFILM (sludge) that protects them and sloughs off to coat tanks and fuel lines as well as clog filters and injectors.

Often, the fight against bacteria and sludge formation is done through the application of biocides. Unfortunately, biocides cannot penetrate the sludge and therefore kill only the planktonic, free-floating bacteria. Using biocides therefore guarantees that sludge formation and MIC corrosion will continue even if the fuel itself has been treated.

Unlike biocides, Fuel Right 15K technology does not kill bacteria. Instead, Fuel Right 15K creates an amine film on the entire fuel delivery system that prevents the formation of sludge and, over time, safely dissolves existing sludge, turning it into small particles that safely pass through filters; both bacteria and the dissolved sludge are burned in the engine cylinders. Fuel Right 15K also enhances injector atomization efficiency, restoring optimal engine efficiency.

TRIAL TEST DESCRIPTION OVERVIEW Testing on Ferry #17 began on 10.20.2014 with both fuel tanks full (7500 liters each); 500 ml, or a treat ratio of 1:15,000 of Fuel Right 15K was added into each tank. A diesel sample was taken; the condition of the ferry fuel filters (Racor), was also noted, as shown here:

Ferry #17 was treated with Fuel Right 15K at every fuel delivery (Mondays and Thursdays) using the same treat ratio; this was continued until April 2015, completing six months as the testing trial period.

It is of important to point out that during the testing period, the normal ferry operating procedures were not changed. Filter changes were made in accordance with scheduled preventive maintenance; as expected, during the initial filter changes, in some cases, given the efficacy of Fuel Right 15K, filters were high impregnated due to dissolution of the sludge biofilm.

During preventive maintenance stoppages, the quality of the fuel was checked; it was verified that the diesel quality was improving and that drastic reduction of sludge in the tank bottom had occurred, a fact evidenced by samples collected during the preventive maintenance stoppages, proving the effectiveness of Fuel Right 15K.

At the end of the trial test period, the elimination of the sludge layer in the tanks was verified as well as the added benefits of eliminating unscheduled ferry stoppages to clean tanks/replace filters, reduction in emissions and no generation of contaminated diesel waste for disposal. The trial also resulted in significant gains in fuel economy and a drastic reduction in changing of filter elements.

In the analysis of fuel consumption, the premises below were assumed:

  1. Since the gain in consumption will be done by comparing two situations (with additive and without additive), as some hour-meter data were not available in these cases we consider the average of two or three engines at the time of reading, since nominally working time is equal for the four engines.

  2. As we did not have the number of hours expended in maintenance stoppages, and as the procedures for preventive maintainability stops were not changed due to the use of Fuel Right 15K, we assume that the ferry was working non-stop, continuously.

  3. The supply information and hour meters were supplied by Dersa.




In this case we assume a sampling period of the last three months, assuming that in this period there was a complete removal of the sludge layer from reservoirs.

TABLE OF DIESEL CONSUMPTION OF FERRY F17 Taking as reference the period between June / 2014 to April / 2015 we have:

ANALYSIS OF FUEL CONSUMPTION OF FERRY F17 Analysis of the previously listed data shows that, in the period from June to October / 2014, the fuel level in the ferry tanks was, on average, very low, with high temperatures inside the tanks, favouring condensation and, as a result, increased water deposition at the bottom of the fuel tanks, the ideal setting for bacterial growth and biofilm formation.


In the analysis of the consumption of filters, two similar sampling periods in which the only variable is use of Fuel Right 15K is used. Thus, the periods from December to March of the following two years were considered; in the second period the impact of Fuel Right 15K was considered:

  • December/2013 to March/2014 → 29 changings of element Racor

  • December/2014 to March/2015 → 16 changings of element Racor

As noted there was a reduction of 45% in consumption of filter elements. A better analysis of dirt in the filters and the resulting pressure drop in the system will lead to a further decrease in consumption of these elements, likely enabling lengthening of the interval between scheduled preventive maintenance.

MACRO FINANCIAL ANALYSIS OF TESTS Once the initial objectives were achieved (eliminating sludge disposal inside the fuel tanks and minimising the number of filter elements changings), the immediate direct gains from use of Fuel Right 15K can be estimated:


  • Average consumption prior to additive --> 3,40 l/h

  • Average consumption after additives --> 3,25 l/h

  • Average consumption after stabilization --> 3,23 l/h

  • Nominal gain in consumption --> 5,0 % (after stabilization)

Assuming an average fuel consumption of around 500,000 liters / month, the fuel economy savings would be 25,000 liters / month.

Taking as reference the price of the diesel in May / 2015, or US$ 0,79 / liter, this gain would be approximately US$ 18,500.00 / month or US$ 222.000,00 / year.


  • Reduction in the consumption in 4 months → 13 filters

  • Reduction projected for one year → 39 filters

Taking as reference the filter price in May / 2015, or US$ 143.00, this gain by ferry would be of US$ 5,572.00 / year. Considering the universe of 33 existing ferries, this gain could reach US$ 184,041.00 / year, or 1287 filters / year.


  • Reduction in fuel consumption --> US$ 222.000,00

  • Reduction projected for a year filters --> US$ 184.041,00

  • Total direct gain --> US$ 404.041,00

D. INDIRECT GAINS FROM THE ADDITIVE In addition to the direct gains listed above, there are several indirect gains that can not be easily measured, for example:

  • Gains in the Hh's resulting from the reduction of stoppages for filter changes.

  • Gains in the Hh's resulting from no need for sludge removal in reservoirs.

  • Increasing the useful life of injector nozzles.

  • Increasing the useful life of reservoirs and fuel distribution lines resulting from the elimination of corrosion processes.

  • Elimination of water dispersion in the diesel, making it deposit directly at the bottom of the reservoirs, thereby enabling its easy drainage.

  • The gains arising from the no need for sludge disposal in the environment.

CONCLUSION This trial demonstrated that regular use of Fuel Right 15K will provide significant operational reliability gains, decreased maintenance, no hazardous disposal issues as well as significant financial benefits from increased fuel economy, reduced filter requirements, in addition to indirect gains listed in paragraph 3.7.f

The efficiency of Fuel Right 15K is confirmed thus justifying the adoption of its use in all ferries operated by DERSA.

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